README.md

RestKit

RestKit is a modern Objective-C framework for implementing RESTful web services clients on iOS and Mac OS X. It provides a powerful object mapping engine that seamlessly integrates with Core Data and a simple set of networking primitives for mapping HTTP requests and responses built on top of AFNetworking. It has an elegant, carefully designed set of APIs that make accessing and modeling RESTful resources feel almost magical. For example, here's how to access the Twitter public timeline and turn the JSON contents into an array of Tweet objects:

Overview

RestKit is designed to be modular and each module strives to maintain a minimal set of dependencies across the framework and with the host platform. At the core of library sits the object mapping engine, which is responsible for transforming objects between representations (such as JSON/XML <-> local domain objects).

Object Mapping Fundamentals

The object mapping engine is built on top of the Key-Value Coding (KVC) informal protocol that is foundational to numerous Cocoa technologies such as key-value observing, bindings, and Core Data. Object mappings are expressed as pairs of KVC key paths that specify the source and destination attributes or relationships that are to be transformed.

RestKit leverages the highly dynamic Objective-C runtime to infer the developers desired intent by examining the type of the source and destination properties and performing appropriate type transformations. For example, given a source key path of created_at that identifies a string within a parsed JSON document and a destination key path of creationDate that identifies an NSDate property on a target object, RestKit will transform the date from a string into an NSDate using an NSDateFormatter. Numerous other transformations are provided out of the box and the engine is pluggable to allow the developer to define new transformations or replace an existing transformation with a new implementation.

The mapper fully supports both simple attribute as well as relationship mappings in which nested to-one or to-many child objects are mapped recursively. Through relationship mappings, one object mapping can be added to another to compose aggregate mappings that are capable of processing arbitrarily complex source documents.

Object mapping is a deep topic and is explored in exhaustive detail in the Object Mapping Guide on the wiki.

API Quickstart

RestKit is broken into several modules that cleanly separate the mapping engine from the HTTP and Core Data integrations to provide maximum flexibility. Key classes in each module are highlighted below and each module is hyperlinked to the README.md contained within the source code.

Describes an object mappable response that may be returned from a remote web application in terms of an object mapping, a key path, a SOCKit pattern for matching the URL, and a set of status codes that define the circumstances in which the mapping is appropriate for a given response.

An NSOperation subclass that sends an HTTP request and performs object mapping on the parsed response body to create NSManagedObject instances, establishes relationships between objects using RKConnectionDescription objects, and cleans up orphaned objects that no longer exist in the remote backend system.

The following Cocoa frameworks must be linked into the application target for proper compilation:

CFNetwork.framework on iOS

CoreData.framework

Security.framework

MobileCoreServices.framework on iOS or CoreServices.framework on OS X

And the following linker flags must be set:

-ObjC

-all_load

ARC

As of version 0.20.0, RestKit has migrated the entire codebase to ARC.

If you are including the RestKit sources directly into a project that does not yet use Automatic Reference Counting, you will need to set the -fobjc-arc compiler flag on all of the RestKit source files. To do this in Xcode, go to your active target and select the "Build Phases" tab. Now select all RestKit source files, press Enter, insert -fobjc-arc and then "Done" to enable ARC for RestKit.

Serialization Formats

RestKit provides a pluggable interface for handling arbitrary serialization formats via the RKSerialization protocol and the RKMIMETypeSerialization class. Out of the box, RestKit supports handling the JSON format for serializing and deserializing object representations via the NSJSONSerialization class.

Additional Serializations

Support for additional formats and alternate serialization backends is provided via external modules that can be added to the project. Currently the following serialization implementations are available for use:

JSONKit

SBJSON

YAJL

NextiveJson

XMLReader + XMLWriter

Installation

The recommended approach for installing RestKit is via the CocoaPods package manager, as it provides flexible dependency management and dead simple installation. For best results, it is recommended that you install via CocoaPods >= 0.19.1 using Git >= 1.8.0 installed via Homebrew.

via CocoaPods

Install CocoaPods if not already available:

$ [sudo] gem install cocoapods
$ pod setup

Change to the directory of your Xcode project, and Create and Edit your Podfile and add RestKit:

Open your project in Xcode from the .xcworkspace file (not the usual project file)

$ open MyProject.xcworkspace

Please note that if your installation fails, it may be because you are installing with a version of Git lower than CocoaPods is expecting. Please ensure that you are running Git >= 1.8.0 by executing git --version. You can get a full picture of the installation details by executing pod install --verbose.